"I'm just trying to count the steps behind me, and there are so many steps," says John Popper, Blues Traveler's harmonica-wielding frontman. Two decades after time-capsule hits like "Run-Around" and "Hook" seemed inescapable, the band that Popper once described as "transcultural" is now transcending genre: Each song on the group's new Blow Up the Moon, out April 7th, features guest artists like 'NSync's JC Chasez, 3OH!3, Hanson, Plain White T's, Jewel and Bowling for Soup. It was recorded in Dave Grohl's Northridge, California, studio. "His vibe is very much in the place," says Popper. "There's a giant portrait of him with a snifter of brandy in the main mixing room. He's got his Hugh Hefner bathrobe on and an ascot, I believe. It's quite a thing to behold."

Related

Why did you collaborate with this particular set of artists?Well, I really gotta give the credit to Lani Sarem, our manager. She really had an idea for a collaboration record, and the artists she had in mind were with Blues Traveler in mind. It seems to me that the coolest thing about us is that we don't know what's cool about us, and so if we actually said, "Hey, who would this band work well with?" I think we'd fuck it up somehow. So you kind of need somebody who's looking at you and saying, "Do you know what's cool about you?" They remind you about a part of yourself that you might dismiss.

What kind of stuff did you get reminded of?It depends on which band we worked with. With Bowling for Soup, I remembered that I like to have fun with lyrics and be funny, and that was also true with Plain White T's. I really remembered I love sounds with 3OH!3. Working with Secondhand Serenade, I just felt like a songwriter, you know, working with another songwriter. How Hanson built a really great system where they become the producers, you can see how this came from the experience they had growing up. They had to forge a place where they could really control the sound they heard in their head. That made us nervous, but our faith was rewarded because when they showed us the product, it was amazing.

You actually worked with them on their second album.Yes! It was so weird working them as adult men, 'cause you just always think of them as kids.

What was it like to work with them 15 years later?The funny part is that back then Taylor had this specific harmonica part in mind. He could play it, and I, for some reason, couldn't play that exact harmonica line. He actually had to do the tagline, and I did all the rest of it. I got to meet their family. It's like the little Hanson brood and they're just running the whole factory, and it's kind of cool. The three of them are telling a story, and at this point I was 400 pounds. Zac goes, "...and he was so fat." Then they all froze and got really embarrassed. I remembered that for 15 years, this weird little Hanson moment. Of course, when we got into the studio, I go, "I remember this moment!" They all wanted to thank me for bringing it back up again [laughs]!

Since JC Chasez is on the album, were you Team 'NSync or Team Backstreet Boys?I tried to skip the whole debate! The thing is, when he showed up, he helped us finish writing the song and had us work on some production ideas. That was a song Tom [Higgenson of Plain White T's] and I had worked on, and he just immediately got it. When he started to talk to you about singing, that's when you remember, "Oh yeah, 'NSync did a lot of vocal work." As he started to lay out the harmonies on "Nikkia's Prom," it really sounds like Plain White Traveler Sync. Imagine those three bands going through the machine that turned that guy into the Fly.

You toyed with hip-hop with the John Popper Project. Did you consider any rappers?That's true, but now what I need is somebody who can vocalize the lyrics like that, or I need to learn how to do that. That's the final step, and then I've really made something hip-hop. I wanna do that again with DJs, some sort of a psychedelic jam.

Who are some of your favorite hip-hop writers then? Like what kind of style are we talking about here? You're gonna laugh, but I like the timing of Bone Thugs-N-Harmony. To me, it was an epiphany as far as cadence goes. I really like 50 Cent, too. I know that I'm dated, but that's what stuck to me.

I would love to hear a Blues Traveler song with 50 Cent.That would be awesome. I think that really the idea with the band is that we want to keep doing this. What sucked is that these were the people whose schedules we could make work. We were so lucky to get these people. We were very happy with the people we got, but we were seeing, like, 50 songs. If we could get album after album where we're doing this, I'll go until the doors fall off. It's a fun way to work – what really helps is having a nice big budget, though. Aw man, give me one of those.

Last year was also the 20th anniversary of Four. What's changed for you and Blues Traveler since that album came out?Well, our hair keeps falling out. But other than that, I don't think anything has changed. I think that big huge record was a fluke. The idea is that we're always going to have a good live show, and we love to pay our music and write well. We really have no reason to stop yet. I think we've created a middle class in rock & roll and we sort of just keep trudging along and having a ball. If this new record is something that really connects to a lot of people, I see it as just a next step.

Some of those songs are still connecting. Did you see Emma Stone lip-sync "Hook" on Jimmy Fallon?Oh my God! It blew me away! First of all, I was moved by every part of that. Even Jimmy Fallon saying, "I forgot about that song" moved me. The fact that she knew it word-for-word and the fact that she sang it with that inflection blew me away. It was a moving thing. I went and bought two tickets to Spiderman2. We did do a response one where I tried to do something from Easy A. I tried to do that dance, but you can tell that I did not put the effort in. All I heard for the next few months was "she totally smoked you!" I'd like to say, officially, that is 100 percent true.